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Molecular characterization of single-chain antibody variable fragments (scFv) specific to Pep27 from Streptococcus

Dongho Kim1, ShinA Jang1, Jihye Oh1

  • 1Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, South Korea.

Biochemical and Biophysical Research Communications
|May 14, 2018
PubMed

Insights

Researchers developed novel antibody fragments to detect Pep27, a key virulence factor in Streptococcus pneumoniae. These tools offer potential for improved diagnostics of pneumococcal diseases.

Area of Science:

  • Immunology
  • Microbiology
  • Biochemistry

Background:

  • Pep27 is a major virulence factor in Streptococcus pneumoniae, initiating bacterial autolysis.
  • Existing antibodies for Pep27 are limited, with no well-characterized monoclonal antibodies available.

Purpose of the Study:

  • To develop and characterize novel antibody fragments for the specific detection of Pep27.
  • To assess the utility of these fragments as diagnostic tools for pneumococcal infections.

Main Methods:

  • Phage display was used to screen a human synthetic scFv library.
  • Selected scFv clones (E2 and F9) were characterized for binding affinity (Kd) and specificity.
  • Epitope mapping was performed using alanine scanning and molecular docking.

Main Results:

  • Two scFv clones, E2 and F9, were selected with dissociation constants of 1.1 μM and 0.50 μM, respectively.
  • E2 and F9 demonstrated high specificity, with no cross-reactivity to other pneumococcal or unrelated proteins.
  • Epitopes were localized to residues 24, 26, and 27 of Pep27, supported by molecular docking.
  • The scFv clones successfully detected Pep27 in human serum, mimicking in vivo conditions.

Conclusions:

  • Developed scFv clones E2 and F9 are specific molecular tools for detecting Pep27.
  • These antibodies show promise for the development of improved diagnostic methods for pneumococcal diseases.
  • Further optimization of scFv affinity could enhance their diagnostic potential.
Keywords:
AffinityEpitopePep27Streptococcus pneumoniaescFv

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